For the trams travelling between cities on normal tracks, thats a relatively new invention, it first came up in about the 1980′s in the region around Karlsruhe and Karlsruhe itself in southwest Germany, hence this is called “Karlsruher Modell” in German.
This is not true! Have you never heard of the great American ‘Interurban’ network? This originated in the last years of the 19th century when electric traction had become a viable proposition. There was a vast network of inter-city interurban lines in the USA that operated for the first four decades of the 20th century; before their rapid demise in the 1950’s when motor cars almost destroyed all US public transportation outside the major cities.
The US interurban network was integrated with the main line railway network, many interurban line operated freight trains conveying main line railroad freight cars. Some even survived carrying freight after ceasing passenger operation.
This would make a great addition to the USA DLC. (Donoteat’s interurban pack goes some way to creating this, but it cannot allow full integration with the railway network due to it being strictly part of the separate tram nework.)